Tapping attachment adapted for numerical control

ABSTRACT

The invention is a tapping attachment of a type having free axial float and automatic depth control. The attachment embodies precise adjustment means for precisely adjusting or controlling the point at which the depth control will release. The depth control includes releasable engagement members movable relatively axially to release. The control means comprises an adjustable limiting member which precisely controls or limits the amount of inward positioning of the driven part of the engagable means relative to the driving part and thereby sets the amount of outward relative movement of the driven part which will cause release. The adjustable limiting means embodies a spring to insure against damage occurring to the attachment in the event the tapping element should encounter the absence of a hole to be tapped.

llit States ,lohnson atent 1191 [54] TAPPHNG ATTACHMENT APTED TOR3,397,588 8/1968 Johnson 408/132 x NUMERICAL CONTROL [75] Inventor:Allan S. Johnson, Newport Beach, Primary Examiner c lil Weidenfeld CalifAttorney, Agent, or Fzrmi-lerz1g & Walsh [73] Assignee: 'llopmaticCorporation, Costa Mesa,

CaIifi [57] ABSTRACT [22] Filed: Dec. 1, 1972 The invention is a tappingattachment of a type having free axial float and automatic depthcontrol. The at- [21] Appl' 311L296 tachment embodies precise adjustmentmeans for pre- Relateol US. Application Data cisely adjusting orcontrolling the point at which the [63] continuatiomimpan of Set No.124,020' March 157 depth control will release. The depth controlincludes 1971, Pat. No. 3,791,756, and a continuation-impart releasableengagement members movable relatlvely of Ser. No. 26,894, April 4, 1970,Pat, No axially to release. The control means comprises an ad-3,717,892. justable limiting member which precisely controls or limitsthe amount of inward positioning of the driven [52] US. Cl. 408/14,408/142, 10/89 F, part of the engagable means relative to the driving10/141 H part and thereby sets the amount of outward relative [51] int.Cl. 823g 3/00 movement of the driven part which will cause release. [58]Field of Search 408/14, 139, 142, 124, The adjustable limiting meansembodies a spring to 408/132; 10/89 H, 89 F, 141 H, 129 R; 192/141insure against damage occurring to the attachment in the event thetapping element should encounter the [56] References Cited absence of ahole to be tapped.

UNITED STATES PATENTS 7 Claims, 8 Drawing Figures 1,915,542 6/1933Lundin et a1. 408/124 g 45 46 X -20 30 u. 7. 22 a! 5:; W g

ee 3 9d 4 s p 5 1 T *r' 92 52 w -84 5 1 24 v0 A74 3 vag /34 E s 7% 4lllll 34 /00 g :5 70 m f 4 60 L. -1

a .v J 1 1 7,1- A .L F 1 l l l V v T T D FOR This application is acontinuation-in-part of U.S. Pat. application Ser. No. 124,020 filed onMar. 15, 1971 now U.S. Pat. No. 3,791,756, and is a continuation-inpartof Ser. No. 26,894 filed on Apr. 4, 1970 now U.S. Pat. No. 3,717,892.

SUMMARY OF THE INVENTION The invention is a tapping attachment of a typehaving automatic depth control. The improvement comprises improvedadjustable means for adjustably controlling accurately a point orposition at which the depth control means will release. The nature ofthe improvement is explained more fully hereinafter.

BACKGROUND OF THE INVENTION U.S. Pat. Nos. 3,041,893 and 3,397,588 arerepre sentative of tapping attachments of types in which the inventionof this application might be embodied. The prior applications referredto above show attachments having depth control in them, as well as meansfor adjusting or controlling the release point of the depth control.Reference is also made to U.S. Pat. Nos. 3,002,206 and 3,472,347.

The depth control means as known, typically comprises a driving part inthe form of a skirt having axial notches in which radial pins in thedriven part engage. In operation, the attachment is being advanced bythe machine while the spindle is rotating to perform the tappingoperation. At a predetermined position under automatic or computercontrol, the advance of the attachment will stop; whereas, the rotationcontinues with tapping continuing until the depth control releases. Itis desired in this type of control to be able to predetermine exactly aposition, that is, the depth at which release will occur to insureaccurate tapping. The depth control adjustment is in the form of anadjustable means which establishes the amount of relative inwardmovement or positioning of the driven part with respect to the drivingpart, that is, the inward movement of the radial pins relative to thenotches in the skirt. This necessarily adjusts or controls the amount ofoutward movement which will cause release and discontinuance of tapping.

The improvements of the herein invention reside in forms of depthcontrol adjustments embodying a spring which biases the adjustmentmeans. The spring is so arranged that the limit position imposed on theinward movement of the driven member is not positive, but rather furtherinward movement can occur upon compression of the spring. Thus, theimprovement insures against breakage or damage which might otherwiseoccur in the event that the tapping bit failed to encounter a hole to betapped, thus forcing unexpected inward movement of the driven part. Theprimary object of the invention is to provide this particular feature,that is, that the depth control adjustment is by way of a spring meansto greater inward movement against the spring bias to avoid the type ofdamage referred to.

Further objects reside in particular improved constructions embodyingthe feature as described. The objective is realized in one form by wayof a threaded collar positioned to position the driving and driven partsrelatively, but to allow inward movement of the floating spindleassembly against the spring biasing means.

A further object is to provide a further improved construction whereinthe adjusting means takes the form of a threaded collar or bushinghaving an associated sliding sleeve with the biasing spring positionedbetween the sleeve and the bushing itself.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and additionaladvantages of the invention will become apparent from the followingdetailed description and annexed drawings, wherein:

FIG. I is a view of preferred form of the attachment mounted in amachine;

FIG. 2 is a cross sectional view of the attachment of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along the line 4--4 of FIG. 2;

FIG. 5 is a view of another form of the attachment mounted in a machine;

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 5;

FIG. 7 is a sectional view taken along the line 77 of FIG. 6; and

FIG. 8 is a sectional view taken along the line 8-8 of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, 10 designatesa machine tool with which the attachment may be used. The tool may be ofa type operated under automatic control such as computer control. Themachine may be of a type having a head carrying multiple spindles, forexample twenty spindles all individually driven. This type of machine isable to drill or tap multiple holes in a work piece at the same time. Itmay be desirable to tap holes of different depth. Numeral l1 designatesgenerally the attachment having a shank or stem part 14 carried by head10. Numeral I3 designates a receptacle: which may be of a type adaptedto receive a quick change chuck assembly.

In FIG. 2, numeral 14 designates a stem which is within head 10 and isdriven and forms a receptacle to receive attachment 11. The attachmenthas a cylindrical shank member 20 having bore 21, the upper part ofwhich is received in bore 22 in cylindrical stem 12. Shank member 20 hasa milled tapered flat 24, and it is held in position by a set screw 26which engages against the flat and by which the amount of insertion isfixed.

Numeral 30 designates a woodruff key which is fitted into an opening 31in the opposite side of shank member 20 and which moves in an axialgroove 32 on the inside of tubular stem 14.

The lower part of member 20 is threaded as shown. Numeral 34 designatesa threaded collar which fits onto the threaded part of the member whichengages against the lower end of the tubular stem 14. It may be set inposition by way of set screw 36 engaging insert 37.

A torque release clutch can be built into the shank 20 of theattachment; or alternatively, a torque release clutch may be built intoa quick change chuck assembly carried by the receptacle I3. Suchalternatives are illustrated in the prior applications referred to.

At the upper end of member there is an end plug or closure member 46carrying a stem 48 as shown. This stem extends down into the tubularspindle 52. The spindle has a longitudinal bore 54. In the upper end ofthis bore is a bushing 56 through which stem 48 extends. At the lowerend of spindle 52, it carries receptacle 13 adapted to rceive a quickchange chuck assembly, not shown. This assembly is like that of theprevious application referred to, Ser. No. 26,894 now US. Pat. No.3,717,892. At the end of bore 54, there is a counterbore 62 whichreceives bearing 64 having a lug 66. Attached to lug 66 is axial floatspring 70 at the other end of which is a hook 72 connected to lug 74 atthe end of stem 48.

The attachment embodies a depth control adjustment. Numeral 80designates a cylindrical member or sleeve having an extending skirt partwith two axial slots in it as designated at 82 and 84. It is biased byspring 86 between it and plug 46. Numerals 90 and 92 designate radialpins carried in bores 94 and 96 in member 20. These pins extend intoslots 82 and 84. Sleeve member 80 of the depth control adjustment ispositioned between spindle 52 and member 20. Numerals 100 and 102designate radial pins fitting in radial bores 104 and 106 in spindlemember 52, as shown. Spindle member 52 can move axially with respect tosleeve member 80 in slots 82 and 84 as will be described.

Numeral 100 designates a bushing fitting between spindle member 52 andmember 20, as shown and held in position by set screws 112 and 114 whichextend through member 20 and engage in an annular recess 116 in bushing110.

Bushing 100 is fixed in position. Accurate means are provided forsetting or adjusting the depth control so as to exactly predetermine thedepth at which the depth control will rlease. The lower end of spindle52 is threaded as designated at 120. Threaded onto the stem is a collar122 having a radial threaded bore 124 receiving a set screw 126.Positioned between collar 122 and the lower end of bushing 110 is abiasing spring 130 which surrounds spindle 52. Collar 122 can beadjusted from a position against receptacle 13 upwardly on threaded part120 of spindle 52 against biasing spring 130. As may be observed, whencollar 122 is adjusted upwardly on spindle 52, it will tend to compressspring 130 to pull spindle 52 downwardly, the radial pins 100 and 102moving downwardly in axial slots 82 and 84. Thus, in this manner, it ispossible to accurately set or adjust the amount of relative downwardmovement of spindle 52 which will cause the radial pins to release fromaxial slots 82 and 84, that is, the depth at which release will occur.

Briefly summarizing the operation, it is as follows. The attachment isoperated by the machine to rotate it and to advance it axially while thetapping element carried by the attachment is tapping into a drilledhole. By automatic control, at a predetermined position of ad vance, themachine will stop the advance of the attachment while it continues torotate the spindle. While continuing to rotate, the tapping element willcontinue to tap into the hole with continued axial advance of spindle 52with radial pins 100 and 102 moving in axial slots 82 and 84 in member80. Depending upon the adjustment, at a predetermined depth, the radialpins will release from the slots. At this point, member 80 movesupwardly against biasing spring 86 to effect release without chatteringwhich is allowed by reason of bevelled surfaces as shown at 134 at oneside of axial slots 82 and 84.

It will be observed that spring provides safety, preventing possiblebreakage under automatic control. In the event for example, that thetapping bit encountered a surface where no hole had been drilled so thatthe spindle was unable to advance, breakage would be prevented since thedrilling element and spindle can be forced inwardly with respect to theattachment against the force of spring 130. The spring and length of theaxial slots in skirt 80 allow considerable relief for relative movementinwardly.

FIGS. 5, 6, 7, and 8 show a modified form of attachment with a differentform of means providing the depth control adjustment. Parts which arethe same as the previous embodiment are identified by the same referencenumerals and the previous description is applicable. Parts which aresimilar but not identical are identified by the same numerals primed,the previous description being applicable except as explainedhereinafter.

In this form of the invention at upper part of member 20, there is anend closure member 131 which has an extending skirt part 132 in whichthere are provided three spaced axial slots 134, 136, and 138 which willbe referred to again presently. Above skirt 132 in member 131, there isa bore 142 and a counterbore 144. In bore 142 is received the end of atubular member 148. In the end of this tubular member, there is a plughaving an end flange 152 and a lug 154 into which is hooked the end ofaxial float spring 70. Spindle 52' has a bore 54. In the upper end ofthis bore is a bushing 56. Tubular member 148 extends down into spindle52', through bushing 56.

The depth control adjustment includes member 160, the upper part ofwhich is designated at 162. This member has a bore 164 and an extendingskirt 166. The extending skirt is of larger diameter. Upper part 162 hasa bore 164. In this bore is bushing through which tubular member 148extends. Numeral 172 designates a biasing spring received in bore 144 inmember 131. The other end bears against depth control member 160. Inupper end 162, there are three radial bores 176, 178, and which receiveradial pins 182, 184, and 186 in the axial slots 134, 136, and 138 inskirt 132 of member 131. Skirt 160 is of a size to fit into bore 21 ofmember 20. Skirt 166 fits around the upper end of spindle member 52'.Formed in skirt 166 are three equally spaced axial slots 170, 172, and174. At the upper end of spindle member 52 there are three, equallyspaced radial bores 180, 182, and 184 which receive radial pins 190,192, and 194 which extend into vertical slots 170, 172, and 174 in skirt166 of member 160. The operation of the depth control will be describedpresently.

In the present form of the invention, the depth control adjustmentcomprises a bushing 200 which is internally threaded as shown and whichis threaded onto member 20' as shown. In the side wall of bushing 200 isa threaded bore 202 which receives set screw 204. Bushing 200 has a part208 of larger diameter as shown. This part has a bore 210. The lower endof the bushing has a bore 212. Slidably fitting on part 208 of largerdiameter of bushing 202 is a sleeve member 220 which is cup shapedhaving an end 222 with bore 224 through which spindle 52 extends. Withinthis sleeve is a biasing spring 230 which surrounds end 232 of bushing2M and bears against the shoulder formed by part 208 of larger diameterof bushing 200, the other end of the spring bearing against the end part222 of sleeve 220. Movement of sleeve 220 outwardly with respect tobushing 2110 is limited by lockwire 236 received within a groove in theend of sleeve 220 to engage the shoulder formed by part 2118 of largerdiameter of bushing 200.

As will be observed, end 222 of sleeve 220 bears against receptacle 13.Spring 230 is under compression.

The operation of this embodiment is similar to the previous embodiment.As may be observed, the adjustment of the bushing or collar member 220downwardly on shank 211' will cause receptacle 13 and spindle 52' tomove downwardly with the radial pins 191], 192, and 194 movingdownwardly in the axial slots 170, 172, and 174 in member 160. In otherwords, by adjustment of collar or bushing 200, the depth controladjustment is made, that is, the depth at which release will occur isprecisely adjusted.

The operation is like that described above. The attachment will beadvanced by the machine to a predetermined position with rotation of thespindle continuing. The spindle will continue to tap into the hole,advancing axially until radial pins 190,192, and 194 disengage fromaxial slots 170, 172, and 174 to bring about release. This occurs at thepredetermined setting of the depth control adjustment. Release isfacilitated by the slanting or bevelled surfaces as shown at 240 on oneside of slot 170. When release occurs, member 162 moves upwardly againstspring 172.

Safety is provided as in the previous embodiment in that should thedrilling element encounter a surface not having a drilled hole,receptacle 13 and spindle 52 will have the freedom to move inwardlyaxially against the force of spring 230 thus avoiding damage. Whenbushing 200 is adjusted outwardly, sleeve 220 moves outwardly and pins190, 192, and 194 adjust outwardly in slots 171 172, and 174.

From the foregoing, those skilled in the art will understand the natureand construction of the invention and the manner in which it achievesand realizes all of the objects and advantages as set forth in theforegoing.

The foregoing disclosure is representative of preferred forms of theinvention and is to be interpreted in an illustrative rather than alimiting sense, the invention to be accorded the full scope of theclaims appended hereto.

What is claimed is:

1. A tapping attachment having a driving part and a driven part, saiddriven part including a tapping spindle; releasable engagement meansbetween the driving part and the driven part constructed to allowrelative axial movement of the driven part carrying the tapping spindle,means normally biasing said parts into engage ment, said releasableengagement means releasing upon an outward axial movement of the drivenpart, the improvement comprising depth control means for predeterminingthe magnitude of axial movement of the driven part relative to thedriving part to disengage said parts, said adjustment means comprisingan adjustable member being adjustably positionable on one of said parts,spring means positioned between the adjustable member and the other ofsaid parts to provide an axial opposed bias between said parts, wherebysaid adjustable member is adjustably positioned on said one part topreset the desired magnitude of relative axial movement of said partswhich will bring about said disengagement.

2. An attachment as in claim 1, wherein said spring means is in the formof a coiled spring encircling the tapping spindle and positioned to becompressed by inward movement of said spindle.

3. A tapping attachment as in claim 2, wherein said adjustable member iscarried by said driven member.

4. An attachment as in claim 3, wherein said adjustable member is in theform of a collar threaded onto the spindle.

5. A tapping attachment as in claim 2, wherein said adjustable member iscarried by the driving member, the spring being interposed between theadjustable member and the driven member.

6. A tapping attachment as in claim 1, wherein said adjustable member isin the form of a bushing and a sleeve slidably carried by the bushingand engageable with the other part.

7. A tapping attachment as in claim 6, wherein said sleeve has an endflange positioned to seat against the other part.

1. A tapping attachment having a driving part and a driven part, saiddriven part including a tapping spindle; releasable engagement meansbetween the driving part and the driven part constructed to allowrelative axial movement of the driven part carrying the tapping spindle,means normally biasing said parts into engagement, said releasableengagement means releasing upon an outward axial movement of the drivenpart, the improvement comprising depth control means for predeterminingthe magnitude of axial movement of the driven part relative to thedriving part to disengage said parts, said adjustment means comprisingan adjustable member being adjustably positionable on one of said parts,spring means positioned between the adjustable member and the other ofsaid parts to provide an axial opposed bias between said parts, wherebysaid adjustable member is adjustably positioned on said one part topreset the desired magnitude of relative axial movement of said partswhich will bring about said disengagement.
 2. An attachment as in claim1, wherein said spring means is in the form of a coiled springencircling the tapping spindle and positioned to be compressed by inwardmovement of said spindle.
 3. A tapping attachment as in claim 2, whereinsaid adjustable member is carried by said driven member.
 4. Anattachment as in claim 3, wherein said adjustable member is in the formof a collar threaded onto the spindle.
 5. A tapping attachment as inclaim 2, wherein said adjustable member is carried by the drivingmember, the spring being interposed between the adjustable member andthe driven member.
 6. A tapping attachment as in claim 1, wherein saidadjustable member is in the form of a bushing and a sleeve slidablycarried by the bushing and engageable with the other part.
 7. A tappingattachment as in claim 6, wherein said sleeve has an end flangepositioned to seat against the other part.